Thermostimulated luminescence properties of CaSO4:Dy and CaSO4:Tm phosphors annealed at high temperatures

Pre-irradiation annealing at temperatures greater than or equal to800 degreesC in air drastically reduces the 230 degreesC dosimetric thermo-stimulated luminescence (TSL) peak in CaSO4: Dy/Tm and simultaneously the 60 degreesC and 120 degreesC peaks are strongly enhanced. In samples sintered at 1000 degreesC, the dosimetric peak vanished totally while the low temperature peaks exhibit a high TSL sensitivity. Moreover, the PL intensities decrease drastically on high temperature sintering; a reduction by as much as 75% is seen at 1000 degreesC. Photo-transfer studies indicate that the 60 degreesC peak might originate from electron release while the 120 degreesC peak from hole release. These two low temperature TSL peaks could have potential applications for photostimulation. (C) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.